One of the troubles with the turf grass on the fairway, putting green and the like of golf courses is dry spot, which is also called localized dry spot or local dry spot, dry patch or dispersed dry spot. The dry spot is damage appearing in patches on the surface of the turf grass due to dryness, which may finally lead to withering of the grass when the condition becomes worse.
The causes of the dry spot have not been completely found out. The reasons are deemed to be uneven water sprinkling, removal of soil surface by rain or sprinkled water, consolidation of soil, soil made water-repellant, and the like.
Specifically, methods of sprinkling particular compounds on the soil are disclosed (JP 2002-20749 A and JP 10-60437 A) to prevent the dry spot from occurring. However, there remain some problems including chemical damage by which the grass turns yellow.